I have a lump on top of my left foot it does not hurt but it seems to be getting bigger and it feels pretty hard

Given : Given that i don't have the benefit of seeing your foot, and not knowing whether there was any history of trauma, the most i can offer is an educated guess, based on the most common "lump" that seems to suddenly develop on the top of the foot, with no injury or underlying disease (like rheumatoid arthritis, etc.). And that would be a ganglion, which is a cyst filled with thick, gelatinous fluid that usually arises from a tendon for no apparent reason. The fluid can be pretty dense and the cyst fairly well packed, giving the appearance of it being hard. They only usually hurt when they press up on a nerve, or with pressure from a shoe. The conservative treatment is to remove the fluid with a needle, and inject a steroid solution. Many times, your doctor would also try to needle it to break up the sac to prevent it from reforming (which is common). If this fails, surgical excision is the other option. The old (probably biblically old) treatment is to whack the thing with a thick book (like a bible). What this attempts to do is break up the cyst. I would caution you to resist doing anything like that, since it almost always reforms after that, and you can injure yourself (and the book). And since we're not 100% certain it really is a ganglion, it's not really prudent to whack an unknown mass with a book! sometimes, these things disappear as quickly as they appear. But considering there are other things that can produce a "lump, " some of which can be serious, i would recommend you see either your family doctor, a podiatrist, or even an orthopedist, all of which can diagnose this thing and give you the proper treatment. Good luck!